1. Field of the Invention
The present invention relates generally to a device and method for aiding the process of loading endoluminal devices into a delivery apparatus. More particularly, the present invention is directed to a device and method to facilitate the collapse of a prosthesis.
2. Description of Prior Art
Endoluminal prostheses such as stents, stent-grafts and other related devices are used to treat vessels that have become weakened or diseased. These prostheses are used in a variety of circumstances to provide a remedy for the damaged vessels. The remedy can come in the form, for example, of added support for a vessel that has become weakened as a result of an aneurysm, or to reopen a vessel in which flow has been restricted due to diseases such as arteriosclerosis.
In order to effectively deliver a prosthesis to the problematic site in the vasculature of the patient, the prosthesis must first be placed within a delivery apparatus, generally including a restrictive sheath or catheter. For example, U.S. Pat. No. 6,096,027, incorporated by reference herein, describes a loading device to compress and load prostheses onto or into a catheter. This is accomplished by placing a stent device into a flexible sleeve or bag, and pulling the bagged stent device through a funnel shaped apparatus. At the end of the funnel taper, a catheter is positioned either to receive the stent device therein, or to accept the stent device thereon. The use of the bag or sleeve to pull the stent device through a funnel-shaped loading apparatus acts to minimize frictional forces inherent in collapsing a stent device from its full diameter, as well as avoiding the longitudinally applied forces associated with pushing a stent device through a loading mechanism.
The loading process described above can be additionally facilitated, particularly for large diameter stent and stent-grafts, by providing further methods to reduce the loading forces. Thus, it is desirable to provide devices and methods for preparing endoluminal prostheses in order to diminish frictional forces acting on the prostheses during the loading thereof into a delivery apparatus.
The present invention relates to devices and methods to facilitate the loading of a prosthesis into a delivery apparatus. More particularly, the present invention is related to devices and methods for forming alterations in the prosthesis to make collapsing of the prosthesis easier by reducing frictional forces acting thereon during the process of loading the prosthesis into a delivery apparatus. Advantageously, creation of alterations in the prosthesis enables a more compact collapse, leading to a smaller insertion profile. This is beneficial to both the physician and patient as complications inherent with the insertion of prostheses are largely reduced.
In preferred embodiments of the present invention, a device to create alterations in a prosthesis includes a grooved mandrel and a pressing comb. The grooved mandrel is preferably a tubular object made from a hard substance, such as stainless steel, with grooves running longitudinally down its length. The grooves are spaced around the circumference of the mandrel, creating two distinct diameters, one for the grooved areas and another for the non-grooved or raised areas. Such a device is also known as a xe2x80x9csplinedxe2x80x9d mandrel to those of skill in the art. The pressing comb is preferably a long hard structure also preferably made of stainless steel, having teeth to create an alteration in a prosthesis without puncturing a layer thereof. The teeth of the comb are therefore extremely short in comparison to a conventional comb. One preferred embodiment of this device additionally includes a coupling apparatus, which not only connects the mandrel and the comb, but also coordinates their actions with respect to one another, mechanically controlling the alteration process.
In a preferred method of utilizing the above-described embodiment of the present invention, the grooved mandrel is placed into the prosthesis, preferably such that a tight fit between the two is achieved, and mounted on a receiving rack. The receiving rack is attached to the coupling apparatus, which is in turn attached to the pressing comb. When the coupling apparatus is activated (i.e., by using a pneumatic control box), the pressing comb is moved a pre-determined distance downward, making contact with the prosthesis (the underlying mandrel being positioned such that a grooved section is facing the comb), until a longitudinal set of alterations is created. The mandrel is then axially rotated until the adjacent grooved section is facing upward and another set of alterations is fashioned. This process is continued until a desired number of sets of alterations are produced.
In other preferred embodiments of the present invention, a device to create alterations in a prosthesis includes a grooved mandrel, a marking wheel and a shaft. The marking wheel can have teeth spaced around its circumference to effectuate an alteration on a prosthesis when the wheel runs along its periphery. In practice, the grooved mandrel is placed within the prosthesis and the shaft is placed through the middle of the marking wheel. The shaft is then used to move the wheel longitudinally down the outside of the prosthesis, forming alterations thereon. Of course, as in the embodiment described above, it would be advantageous to utilize a coupling apparatus to coordinate the formation of the alterations on the desired portion of the prosthesis.
These and other features and advantages of the present invention will become more apparent to those skilled in the art when taken with reference to the following more detailed description of the preferred embodiments of the invention and the accompanying drawings.